Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q19/00—Preparations for care of the skin
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/72—Cosmetics or similar toiletry preparations characterised by the composition containing organic macromolecular compounds
  • A61K8/81—Cosmetics or similar toiletry preparations characterised by the composition containing organic macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
  • A61K8/8105—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • A61K8/8111—Homopolymers or copolymers of aliphatic olefines, e.g. polyethylene, polyisobutene; Compositions of derivatives of such polymers
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q9/00—Preparations for removing hair or for aiding hair removal
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q1/00—Make-up preparations; Body powders; Preparations for removing make-up
  • A61Q1/02—Preparations containing skin colorants, e.g. pigments
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q1/00—Make-up preparations; Body powders; Preparations for removing make-up
  • A61Q1/02—Preparations containing skin colorants, e.g. pigments
  • A61Q1/04—Preparations containing skin colorants, e.g. pigments for lips
  • A61Q1/06—Lipsticks

Definitions

• This invention relates to a novel external agent for application to the skin, and more specifically, to a novel external agent for the skin comprising a liquid low-molecular-weight ethylenic copolymer and having freedom from skin irritation, low dependence of viscosity on temperature, a low pour point, and excellent storage stability, colorless transparency, non-tasty and non-odorous characteristics and an excellent feed of use.
• Oily substances such as liquid paraffin and liquid hydrogenated isoprene oligomer are used as bases (base oils) of external agents for the skin such as cosmetics in ordinary applications.
• Squalane, hydrogenated products of squalane is also used as basis of luxurious cosmetics.
• squalane is characterized by causing little skin irritation and toxicity and having low dependence of its viscosity on temperature, a low viscosity, a low pour point and an excellent feel of use. Since, however, squalane is produced from shark liver oil, a natural product, its price fluctuates greatly with the scarcity of resources and is also high.
• oily substances such as liquid paraffin, liquid hydrogenated isoprene oligomer and liquid polyisobutylene have inferior performances in respect of skin irritation, the low dependence of viscosity on temperature, fluidity, storage stability, and a feel of use, and cannot be used in high-quality luxurious articles as bases for cosmetics and the like.
• a non-irritant topical skin preparation comprising a liquid low-molecular-weight ethylenic copolymer having
• the liquid low-molecular-weight ethylenic copolymer to be incorporated in the external agent for the skin in accordance with this invention has an ethylene component content of 30 to 70 mole %, preferably 35 to 65 mole %, especially preferably 40 to 60 mole %, and an alpha-olefin component content of 30 to 70 mole %, preferably 35 to 65 mole %, especially preferably 40 to 60 mole %.
• the ethylene component content of the liquid low-molecular-weight ethylenic copolymer exceeds 70 mole % and the content of the alpha-olefin component is less than 30 mole %, the external agent for the skin has a high pour point and a degraded appearance (becomes muddy). If the ethylene component content is less than 30 mole % and the alpha-olefin component content exceeds 70 mole %, the dependence of the viscosity on temperature of the external agent is high and its storage stability is degraded.
• alpha-olefin component constituting the liquid low-molecular-weight ethylenic copolymer examples include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicocene.
• the number average molecular weight ( M n) of the liquid low-molecular-weight ethylenic copolymer determined by gel permeation chromatography (GPC) is 200 to 4,500, especially preferably 450 to 4,000. If the number average molecular weight of the ethylenic copolymer is less than 150, the storage stability of the external agent is reduced and it becomes irritating to skin. If its number average molecular weight exceeds 5,000, the external agent has a higher pour point and an increased viscosity so that its handling becomes difficult.
• the Q value (weight average molecular weight/number average molecular weight) determined by the GPC analysis method, of the ethylenic copolymer is not more than 4, preferably not more than 3, especially preferably not more than 2.5. If the Q value exceeds 4, the external agent becomes irritating to skin.
• the standard deviation value ( ⁇ ) of the ethylene component content of the ethylenic copolymer is not more than 3, preferably not more than 2, especially preferably not more than 1. If this standard deviation value ( ⁇ ) becomes greater than 3, the appearance (colorless transparency) of the external agent becomes muddy.
• the ethylenic copolymer in accordance with this invention further has a B value, defined by the following formula (I), of 1.0 ⁇ B ⁇ 1.5 (II) .
• P E represents the molar fraction of the ethylene component content of the copolymer
• P0 represents the molar fraction of the alpha-olefin component content
• P 0E represents the molar fraction of the alpha-olefin/ethylene chains in the entire dyad chains.
• the B value is an index showing the sequence distribution of the individual monomer components in the copolymer chain. Larger B values show less block-like chains and the more uniform distribution of ethylene and alpha-olefin.
• liquid low-molecular-weight ethylenic copolymer in accordance with this invention has the following B values.
• the copolymer has an ethylene content of not more than 50 mole %:- 1.0 + 0.2 x P E ⁇ B ⁇ 1 (1 - P E ) , more preferably 1.0 + 0.3 x P E ⁇ B ⁇ 1/(1 -P E ) , especially preferably 1.0 + 0.4 x P E ⁇ B ⁇ 1/(1 - P E ) .
• the copolymer has an ethylene content of at least 50 mole %:- 1.2 - 0.2 x P E ⁇ B ⁇ 1/P E , more preferably 1.3 - 0.3 x P E ⁇ B ⁇ 1/P E , especially preferably 1.4 - 0.4 x P E ⁇ B ⁇ 1/P E .
• the liquid low-molecular-weight ethylenic copolymer in accordance with this invention can be produced by purifying (for example, by treating with activated carbon) the product synthesized in accordance with the method proposed in Japanese Laid-Open Patent Publication No. 123205/1982 and Japanese Patent Application No. 259835/1985 filed by the present applicant under properly selected polymerization conditions.
• the above ethylenic copolymer is incorporated as a base in the external agent for the skin provided by this invention, and various additives for external agents for application to the skin such as ordinary cosmetics, pharmaceuticals and quasi-drugs may be incorporated.
• oils such as hair cosmetics, hair-washing cosmetics, face lotions, creams, lotions, packs, foundations, powders, rouges, eyebrow cosmetics, eyelash cosmetics, cheek cosmetics, nail cosmetics, bathing cosmetics, and cosmetic oils; hair removers; and ointments.
• composition and physical property values of the liquid low-molecular-weight ethylenic copolymers used in the external agents for the skin according to the invention were measured and evaluated by the following methods.
• M n and M w were measured as follows in accordance with "Gel Permeation Chromatography” by Takeuchi, published by Maruzen Co., Ltd.
• the sample preparing conditions and the GPC measuring conditions at this time were as follows.
• the average molecular weights described in the present specification and claims was obtained by correcting Mn calculated for polystyrene, by using squalane of a known molecular weight.
• the sample of ethylenic copolymer was extracted with a mixture of acetone and hexane at varying mixing ratios using a separating funnel by the following method and under the following conditions, and divided into three fractions of different compositions.
• 40g of the sample was precisely weighted and dissolved in 300 ml of hexane.
• the solution was put in a separating funnel. At 25°C, 500 ml of acetone was added (the volume ratio of hexane/acetone was 5/3), and the funnel was shaken. On settling, the solution separated into two layers. The lower layer was designated as a fraction solution 1. Then, 400 ml of acetone was further added to the upper layer. The mixture was shaken and then allowed to settle, whereby it separated into two layers.
• the lower layer was designated as a fraction solution 2, and the upper layer was designated as a fraction solution 3.
• the content of ethylene in each of these fractions was determined by 13C-NMR analysis, and using the content and weight fraction of ethylene in each of the fractions, the standard deviation ( ⁇ ) of the content of ethylene was calculated in accordance with the following formula. A larger standard deviation value shows a broader ethylene composition distribution.
• Ei represents the ethylene content of the i fraction
• E represents the average ethylene content of the copolymer.
• the B value of the liquid low-molecular-weight ethylenic copolymer is defined as follows:- wherein P E represents the molar fraction of the ethylene component content of the copolymer, P 0E r represents the molar fraction of the alpha-olefin component content, and P 0E represents the molar fraction of the alpha-olefin/ethylene chain in the entire dyad chains.
• the B value is an index showing the sequence distribution of the individual monomer components in the copolymer, and is calculated by determining P E , P0 and P OE in the above definition in accordance with the descriptions of G.J. Ray: Macromolecules, 10 , 773 (1977); J.C. Randall: Macromolecules, 15 , 353 (1982); J. Polymer Science, Polymer Physics, Ed., 11 , 275 (1973); and K. Kimura: Polymer, 25 , 441 (1984).
• a larger B value shows less block-like chains and the more uniform distribution of ethylene and alpha-olefin.
• the B value was determined and calculated as follows:- The 13C-NMR spectrum of a sample prepared by uniformly dissolving about 200 mg of the copolymer in a 10 mm ⁇ sample tube which contains 1 ml of hexachlorobutadiene was measured under the following conditions. And then, from determined P E , P0 and P OE , the B value was calculated.
• Measuring temperature 120°C Measuring frequency: 25.05 MHz Spectrum width: 1500 Hz Filter width: 1500 Hz Pulse repeating time: 4.2 sec Pulse width: 7 ⁇ sec. Integration: 2000 to 5000 times
• the A value of the liquid low-molecular-weight copolymer is measured by the following method.
• a 5 % by weight n-hexane (for spectral use) solution of the copolymer was put in a cell having a thickness of 10 mm, and its UV absorption spectrum was measured at a wavelength between 250 and 280 nm. In the resulting UV absorption spectrum, the absorbance in the maximum absorption wavelength region was defined as the A value.
• This test was conducted by a pre-incubation technique using Salmonella typhimurium TA98, TA100, TA1535 and TA1537, and Escherichia coli WP2uvrA as test microorganism strains.
• Vaseline was coated on an aluminum dish and a filter paper was put on it. A moderate amount of the sample copolymer was infiltrated in the paper, and the filter paper was applied to the inside of the upper arm of a human subject. About 48 hours, it was removed and the state of the skin surface was observed with unaided eyes under natural light 5 minutes and 60 minutes after the removal. The results of observation were rated on the following standards of evaluation.
• a lipstick was made in accordance with an existing recipe (squalane incorporated Lab. No. U948-F) except that the copolymer in accordance with this invention was used instead of squalane and then subjected to a stability test.
• the lipstick was observed for three months at 5°C, room temperature, 40°C, 50°C, and a cycle of these temperatures.
• the appearance, the applied color and the feel of use of the lipstick were compared with those of a control lipstick stored at room temperature.
• liquid low-molecular-weight ethylenic copolymers in accordance with the present invention can be produced by purifying crude copolymers synthesized by the methods disclosed in Japanese Laid-Open Patent Publication No. 123205/1982 and 259835/1985.
• an ethylene/propylene copolymer was synthesized continuously. Specifically, 5 liters/hr of hexane, 4 liters/hr of a hexane solution of vanadyl trichloride (15 millimoles/liter), and 1 liter/hr of a hexane solution of ethyl aluminum sesquichloride (360 millimoles/liter) were continuously fed into the reactor from its upper portion. Ethylene and propylene gases were fed from the upper portion of the reactor at a rate of 96 liters and 100 liters per hour, respectively.
• Ethylene content 53 mole % Number average molecular weight: 410 Q value: 1.11 ⁇ : 0.1 B value: 1.2 A value: less than 0.01 Kinematic viscosity at 100°C: 4.55 cST Viscosity index: 153 Pour point: less than -60°C Color (APHA): 5 Iodine value: less than 0.5 Specific gravity (d 20 4 ): 0.808 Refractive index (n 25 D ): 1.450 Acid value: less than 0.01 Appearance: colorless transparent non-odorous liquid
• Example 1 was repeated except that a hexane solution of vanadyl ethoxydichloride (10 millimole/liter) was used instead of the hexane solution of vanadyl trichloride; the concentration of the hexane solution of ethyl aluminum sesquichloride was changed to 240 millimoles/liter; the feed rates of the ethylene and propylene gases were changed to 84 liters and 196 liters per hour respectively; and hydrogen gas was fed so that the gas phase pressure of the reactor reached 13 kg/cm2G.
• the rate of production of the crude copolymer was 120g per hour, and the final purified copolymer had the following properties.
• Ethylene content 48 mole % Number average molecular weight: 270 Q value: 1.05 ⁇ : 0.1 B value: 1.2 A value: less than 0.01 Kinematic viscosity at 100°C: 1.83 cST Pour point: less than -60°C Color (APHA): 5 Iodine value: less than 0.5 Specific gravity (d 20 4 ): 0.788 Refractive index (n 25 D ): 1.441 Acid value: less than 0.01 Appearance: colorless transparent non-odorous liquid
• Example 1 was repeated except that a hexane solution of vanadyl ethoxydichoride (2.5 millimoles/liter) was used instead of the vanadyl trichloride solution; the concentration of the hexane solution of ethyl aluminum sesquichloride was changed to 80 millimoles/liter; the feed rates of the ethylene and propylene gases were changed to 360 liters and 540 liters per hour, respectively; and hydrogen gas was fed so that the gas phase pressure of the reactor reached 7 kg/cm2. The rate of production of the crude polymer was 950 g per hours.
• the final purified copolymer had the following properties.
• Ethylene content 54 mole % Number average molecular weight: 3200 Q value: 2.54 ⁇ : 0.1 B value: 1.2 A value: less than 0.01 Kinematic viscosity at 100°C: 1740 cST Pour point: -5°C Viscosity index: 300 Color (APHA): 5 Iodine value: less than 0.5 Specific gravity (d 20 4 ): 0.849 Acid value: less than 0.01 Appearance: colorless transparent non-odorous liquid
• a 4-liter glass reactor equipped with stirrer was used, and an ethylene/1-decene copolymer was continuously synthesized at atmospheric pressure. Specifically, 1 liter/hr of hexane as a solvent, 1 liter/hr of a hexane solution of vanadyl trichloride, (16 millimoles/liter) and 1 liter/hr of a hexane solution of ethyl aluminum sesquichloride (96 millimols/liter) were continuously fed into the reactor from its upper portion. Ethylene gas, hydrogen gas and 1-decene were fed respectively from the upper portion of the reactor at a rate of 36 liters, 180 liters, and 1 liter per hour, respectively.
• reaction mixture was continuously withdrawn from the lower portion of the reactor so that the amount of the reaction mixture in the reactor was always maintained at 2 liters.
• the reaction temperature was adjusted to 35°C by circulating hot water through a jacket fixed to the outside portion of the reactor. Methanol was added to the reaction mixture withdrawn from the lower portion of the reactor to stop the polymerization reaction. Then, the reaction mixture was washed with water three times, and then distilled under a reduced pressure of 4kPa (30 mm Hg) at a pot temperature of 100°C to remove the hexane solvent.
• the resulting crude copolymer was a liquid ethylene/1-decene copolymer having an ethylene content of 44 mole % and an iodine value of 9.4.
• the crude copolymer was subjected to hydrogenation in the presence of Raney nickel at 150°C under a hydrogen pressure of 50 kg/cm2G. Then, the product was subjected to topping and activated carbon treatment as in Example 1 to give a purified copolymer having the following properties.
• Example 1 was repeated except that 1.5 liters/hr of hexane, 2.5 liters/hr of a hexane solution of vanadyl ethoxydichloride (1.8 millimoles/liter) instead of the hexane solution of vanadyl trichloride, 1 liter/hr of a hexane solution of ethyl aluminum sesquichloride (45 millimoles/liter), 258 liters/hr of ethylene gas and 165 liters/hr of propylene gas were fed continuously, and hydrogen gas was fed so that the gas phase pressure of the reactor reached 5.7 kg/cm2G. The rate of production of the crude copolymer was 420 g per hour.
• the final purified copolymer had the following properties.
• Ethylene content 75 mole % Number average molecular weight: 4500 Q value: 2.05 ⁇ : 0.3 B value: 1.2 A value: less than 0.01 Pour point: +20°C Iodine value: less than 0.5 Acid value: less than 0.01 Appearance: white semi-transparent non-odorous liquid
• Example 1 was repeated except that the rates of feeding the ethylene and propylene gases were changed to 5 liters and 100 liters per hour, respectively, and hydrogen gas was fed so that the gas phase pressure of the reactor reached 10 kg/cm2G.
• the rate of production of the crude copolymer was 550 g per hour, and the final purified copolymer had the following properties.
• Ethylene content 10 mole % Number average molecular weight: 810 Q value: 2.21 ⁇ : 0.1 B value: 1.15 A value: less than 0.01 Kinematic viscosity at 100°C: 30.0 cST Viscosity index: 60 Pour point: -25°C Iodine value: less than 0.5 Acid value: less than 0.01 Appearance: colorless transparent non-odorous liquid
• Example 2 was repeated except that the distillate obtained at the time of topping was further distilled at 100°C under 400Pa (3 mmHg) and the distillate was collected and treated with activated carbon in the same way as in Example 1.
• the final purified copolymer had the following properties.
• Ethylene content 47 mole % Number average molecular weight: 120 Q value: 1.07 ⁇ : 0.1 B value: 1.2 A value: less than 0.01 Pour point: less than -60°C Color (APHA): 5 Iodine value: less than 0.5 Acid value: less than 0.01 Appearance: colorless transparent non-odorous liquid
• an ethylene/propylene copolymer was continuously synthesized at atmospheric pressure. Specifically, 1 liter/hr of hexane as a solvent, 2 liters/hr of a hexane solution of vanadyl ethoxydichloride (1.2 millimoles/liter), and 1 liter/hr of a hexane solution of ethyl aluminum sesquichloride (14.4 millimoles/liter) were continuously fed into the reactor from its upper portion. Furthermore, from the upper portion of the reactor, ethylene gas, propylene gas and hydrogen gas were fed into the reactor at a rate of 170 liters, 110 liters and 18 liters per hour, respectively.
• reaction mixture was continuously withdrawn from the lower portion of the reactor so that the amount of the reaction mixture in the reactor was always maintained at 2 liters.
• the reaction temperature was adjusted to 35°C by circulating hot water through a jacket fixed to the outside portion of the reactor.
• the reaction mixture withdrawn from the lower portion of the reactor was treated in the same way as in Example 1 to obtain a crude copolymer at a rate of 250 g per hour.
• the resulting final purified copolymer had the following properties.
• Ethylene content 59 mole % Number average molecular weight: 8600 Q value: 2.25 ⁇ : 0.1 B value: 1.2 A value: less than 0.01 Pour point: +50°C Cor (APHA): 5 Iodine value: less than 0.5 Acid value: 0.01 Appearance: colorless transparent non-odorous liquid
• a 1.5 liter glass reactor equipped with stirrer and a dropping funnel was fully purged with nitrogen, and 800 ml of dehydrated deaerated hexane and then 2.34 ml of diisobutyl aluminum chloride were charged into the reactor. Then, a gaseous mixture of ethylene, propylene and hydrogen (14.4, 21.6 and 144 liters per hour, respectively) was fed from the upper portion of the reactor. 10 minutes after the initiation of feeding the gaseous mixture, 2.22 ml of a 6.67 % hexane solution of diethoxy chlorovanadate was added dropwise from the dropping funnel, and the copolymerization of ethylene and propylene was carried out. Thereafter, 10 ml of methanol was added to stop the polymerization. The resulting reaction mixture was treated in the same way as in Example 1 to give a purified copolymer having the following properties.
• Example 1 was repeated except that a hexane solution of vanadyl ethoxydichloride was used instead of the hexane solution of vanadyl trichloride; the feed rates of the ethylene and propylene gases were changed to 160 liters and 240 liters per hour, respectively; hydrogen gas was fed so as to provide an gas phase pressure of 4.5 kg/cm2 in the reactor; and the reaction temperature was adjusted to -5°C . The rate of production of the crude copolymer was 800 g per hour.
• the final purified copolymer had the following properties.
• Ethylene content 50 mole % Number average molecular weight: 400 Q value: 1.56 ⁇ : 3.2 B value: 1.15 A value: less than 0.01 Iodine value: less than 0.5 Acid value: less than 0.01 Appearance: colorless transparent non-odorous liquid
• a 1.5-liter glass reactor equipped with stirrer was fully purged with nitrogen, and 800 ml of dehydrated deaerated hexane and then 10 ml of diethyl aluminum chloride were fed into the reactor. Thereafter, a gaseous mixture of ethylene, propylene and hydrogen (75, 75 and 150 liters per hour respectively) was fed into the reactor from its upper portion. 10 minutes after the initiation of feeding the gaseous mixture, 1.54 g of titanium trichloride was introduced. The reaction temperature was adjusted to 70°C and the polymerization was carried out for 30 minutes. Thereafter, 10 ml of methanol was added to stop the polymerization reaction. The resulting reaction mixture was treated as in Example 1 to give a final purified copolymer having the following properties.
• Ethylene content 45 mole % Number average molecular weight: 1500 Q value: 3.14 B value: 0.84 Appearance: white non-transparent non-odorous greasy substance.
• the purified coplymers obtained in Examples 2 and 3 were subjected to a mutagenicity test using microorganisms in order to examine carcigogenicity.
• the results obtained with these copolymers were rated "negative" in the above test because in any of the microorganism strains used, reverse mutants in number twice the number of natural reverse mutants were not observed.
• Example 2 The final copolymer obtained in Example 2 was subjected to an irritant effects on human body (patch test) by 20 subjects. The results showed no positive subject and 20 negative subjects both 5 minutes and 60 minutes later. As in the results of a test conducted on squalane for cosmetics, the above copolymer was found to be safe on the human body.
• Lipsticks were produced in accordance with a known lipstick formulation (squalane incorporated Lab. No. U948-F) except that the final copolymer products obtained in Examples 1, 2 and 3 were used instead of squalane.
• the lipsticks were subjected to a stability test. The results obtained with the copolymers prepared in Examples 1, 2 and 3 were not different from the test results obtained in a blank test using U948-F (sqalane).
• the ingredients (1) to (9) were mixed and heated to 75°C.
• a mixture of the ingredients (10) to (13) was heated to 75°C, and gradually added to the above mixture, and the mixture was emulsified.
• the emulsion was cooled, and the ingredient (14) was added to form the above product.
• the ingredients (1) to (6) were heated and dissolved homogeneously, and the ingredient (7) was added. The mixture was cooled to form the above product.
• the ingredients (1) to (6) were mixed and heated to 75°C.
• a mixture of the ingredients (7) to (15) were heated to 75°C and gradually added to the above mixture.
• the mixture was emulsified and cooled.
• the ingredient (16) was finally added to form the above product.
• the ingredients (1) to (9) were heated and homogeneously dissolved.
• the ingredients (10) to (13) were added.
• the mixture was cooled, and homogeneously kneaded by a roll mill.
• the mixture was heated to 80°C, and the ingredient (14) was added.
• the mixture was defoamed, cast into a mold, and rapidly cooled to form the above product.

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• 1986
  • 1986-12-01 JP JP61284259A patent/JPH072617B2/ja not_active Expired - Lifetime
• 1987
  • 1987-12-01 CN CN87105958A patent/CN1017964B/zh not_active Expired
  • 1987-12-01 CA CA000553189A patent/CA1326824C/en not_active Expired - Fee Related
  • 1987-12-01 DE DE8787310560T patent/DE3785158T2/de not_active Expired - Fee Related
  • 1987-12-01 EP EP87310560A patent/EP0270339B1/en not_active Expired - Lifetime
  • 1987-12-01 KR KR1019870013645A patent/KR920004092B1/ko not_active IP Right Cessation
• 1989
  • 1989-08-01 US US07/390,504 patent/US4960875A/en not_active Expired - Lifetime

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